In many countries telecommunications operators and Internet service providers are today obliged by legal requirements to provide Law Enforcement Agencies (LEAs) with stored traffic data generated from public telecommunications for the purpose of detection, investigation and prosecution of crime and criminal offences.
A system for accessing communications related data is the well known Lawful Interception (LI) system. The standard architecture comprises Intercepting Control Elements (ICEs) providing the user equipment of the target user with an access to the telecommunications network. An Intercepting Control Element may be, for instance, a 3G Mobile service Switching Center (MSC) Server, a 3G Gateway MSC Server, a Serving GPRS Support Node (SGSN), or a Gateway GSN (GGSN).
The architecture may further comprise one or more Law Enforcement Monitoring Facilities (LEMFs) through which respective Law Enforcement Agencies receive interception information.
An Administration Function (ADMF) entity may be configured for sending the target identity and Lawful Interception authorisation data from the Law Enforcement Agencies to the Intercepting Control Elements.
Every physical Intercepting Control Element may be linked to the ADMF by means of its own X1_1 interface. Consequently, every single Intercepting Control Element may perform interception, i.e. activation, deactivation, interrogation as well as invocation, independently from other Intercepting Control Elements.
2G/GSM and 3G/UMTS are key mobile communication technologies, used by more than two-billion people around the world. In order to adapt to new services, increasing demand for user bandwidth, quality of service and requirements for network convergence, evolutions are often introduced in 3G network standard.
In this context, Evolved Packet System (EPS) is a major evolution of the 3G/UMTS standard introduced by the 3rd Generation Partnership Project (3GPP) standard committee. EPS is defined by 3GPP in Release 8 as an entirely new core network with a flatter all-IP architecture enabling a higher data rate and lower latency packet optimised system that supports multiple radio access technologies, focusing on the packet-switched domain.
In view of the widespread diffusion of 2G and 3G technologies, 3GPP specifications allow 2G/3G networks to interwork with Evolved Packet System, a situation that frequently happens e.g. whenever a 2G/3G terminal is used in a network whose operator has also deployed Evolved Packet System.
3GPP specifications include functional requirements for Lawful Interception. Technical specification ETSI DTS/LI-00039 gives guidance for the delivery and associated issues of retained data of telecommunications and subscribers. In particular, such specification provides a set of requirements relating to Handover Interfaces for the retained traffic data and subscriber data by law enforcement and other authorized requesting authorities. Technical Specification ETSI DTS/LI-00033 contains handover requirements and a handover specification for the data that is identified in EU Directive 2006/24/EC on retained data.
In case of interworking between 2G/3G and the Evolved Packet System, Lawful Interception is to be performed in different nodes, in particular in three different nodes where, in some cases, two nodes out of three may belong to the same network. This situation creates multiple instances of intercept products for the same target subscriber, a situation that may negatively affect the performance of the nodes involved in Lawful Interception, on the side of both the operator and of the Law Enforcement Agency, in terms of bandwidth and, in general, in terms of usage of resources.